The atomic-scale structure of LaCrO-NaTaO solid solution photocatalysts with enhanced electron population

Visible light sensitization of sodium tantalate (NaTaO 3 ), a highly UV-active material, is critical for realizing its practical application in photocatalytic water splitting under solar light. Double doping of a half-filled transition metal together with another metal for cationic charge balance is a promising way of sensitizing NaTaO 3 to visible light. One fundamental issue is that the atomic-scale structure of such doubly doped NaTaO 3 is not yet fully understood. In this study, we doubly doped NaTaO 3 with La 3+ and Cr 3+ through a solid-state route. The occupation preference of La 3+ in a doubly doped system was particularly studied by the extended X-ray absorption fine structure technique. We revealed the substitution of La 3+ for Na + , and Cr 3+ for Ta 5+ , forming a LaCrO 3 -NaTaO 3 solid solution. We then showed that doping NaTaO 3 with La 3+ and Cr 3+ appreciably increased the population of electrons photoexcited by either visible light or UV light. Photoactivation of the doubly doped NaTaO 3 with visible light produced a population of electrons comparable to that under UV light. The charge compensation scheme of double doping with La 3+ and Cr 3+ is shown here to be a good option for the sensitization of NaTaO 3 to visible light. The atomic-scale structure of a NaTaO 3 photocatalyst doped with La 3+ and Cr 3+ for visible light sensitization is successfully revealed.